Engine fault diagnostics (VW Golf 4)

If the engine does not work, it is necessary to systematically eliminate the faults. In order for a gasoline engine to work, two conditions must be met: the fuel-air mixture must be supplied to the engine cylinders and a spark must jump between the spark plug electrodes. First of all, it is necessary to check for a spark on the spark plugs.

Execution order

1. Remove the spark plug and secure it to the engine cylinder block.

2. Connect the high-voltage wire to the spark plug. Hold the spark plug with special pliers with insulated handles.

3. While turning the engine with the starter, check for a spark between the spark plug electrodes.

Warning: When checking for a spark between the spark plug electrodes, gasoline should not be supplied to the engine, as this will damage the catalytic converter. To do this, disconnect the electrical connectors from the fuel injectors. If a spark jumps between the spark plug electrodes, the ignition system is OK.

(The original text can be found on the portal: vwmanual.ru)

CAUSE	METHOD OF ELIMINATION
Difficulty starting the engine or the engine does not start
Incorrect actions when starting a gasoline engine	Apply the handbrake and depress the clutch. On models with an automatic transmission, set the selector lever to the "P" or "N" position. Start the engine by turning the ignition key and release the ignition key after the engine starts. Do not press the accelerator pedal. You can start driving immediately after starting the engine, even in winter. If the engine does not start after turning the engine with the starter for 10 seconds, interrupt the engine starting process and repeat it after at least 30 seconds. Several consecutive attempts to start the engine can damage the catalytic converter, since unburned fuel gets into the exhaust system and settles on the catalytic converter cells. When starting a hot engine, after the engine starts, slightly press the accelerator pedal
Low compression in engine cylinders	Replace the cylinder head gasket or overhaul the engine
Faulty fuse for: - electric fuel pump, - electronic injection system	Check the fuses
Fuel system malfunction	The system is contaminated, the pipeline is bent or deformed. Check the amount of fuel supplied.
The starter turns the engine very slowly	Charge the battery. Check the electrical circuit of the starter
Incorrect valve timing	Check the valve timing. Check the timing belt tension